THURSDAY, 15 APRIL 2021The stereotypical primate hand is considered a highly optimized grasping structure, adapted to life on trees and useful for grabbing tools. Much of the credit for this is given to the ‘opposable thumb’, the digit on the hand which can bend to oppose the others in its movement and position. Having a thumb allows for grasping, but it is not just specific to primates; some birds and frogs are known to have similar anatomical capabilities. New research, however, has revealed the world’s oldest known opposable thumb, and it belongs to the appropriately named ‘Monkeydactyl’. This is the first evidence of such a structure in pterosaurs.
Kunpengopterus antipollicatus is the official name for the new species of Jurassic pterosaur, which was described in a recent paper published in Current Biology. The preserved specimen was small, had a wingspan of 85cm, and had a clearly preserved opposable “pollex” (the anatomical name for thumb) on both hands as its distinguishing feature, hence it being named ‘antipollicatus’. Using micro-computed tomography (micro-CT), a technique which involves X-ray imaging, the research team behind the discovery were able to study its forelimb musculature and morphology, concluding that it likely had an arboreal lifestyle. This differs from other pterosaurs in its ecosystem, which likely were not arboreal, and provides the first definitive evidence that at least some pterosaur species were tree-dwelling.
Co-author of the study and PhD researcher at the University of Birmingham Fion Waisum Ma, said about the discovery: "The fingers of 'Monkeydactyl' are tiny and partly embedded in the slab. Thanks to micro-CT scanning, we could see through rocks, create digital models and tell how the opposed thumb articulates with the other finger bones. This is an interesting discovery. It provides the earliest evidence of a true opposed thumb, and it is from a pterosaur - which wasn't known for having an opposed thumb”
Adiyant Lamba is a PhD student studying developmental biology, and News Editor at BlueSci.